The present invention relates to a liquid ejecting head which ejects any of various types of liquids in the form of droplets, and to a liquid ejecting apparatus having the liquid ejecting head; for example, an image recording apparatus such as an ink jet printer, a display manufacturing apparatus for manufacturing a display or the like, an electrode formation apparatus which forms electrodes, and a chip manufacturing apparatus for manufacturing chips.
A liquid ejecting apparatus has an ejection head and ejects (discharges) any of various types of liquids from the ejection head. For example, the liquid ejecting apparatus is an image recording apparatus, such as an ink jet printer or an ink jet plotter. However, the liquid ejecting device has recently been applied to various pieces of manufacturing apparatus while the ability to accurately supply a nominal volume of liquid to a predetermined position is exploited. For instance, the liquid ejecting apparatus is applied to a display manufacturing apparatus for manufacturing a color filter of a liquid-crystal display, an electrode forming apparatus for forming electrodes for an organic Electro Luminescence (EL) display and an FED (Field Emission Display), and a chip manufacturing apparatus for manufacturing biochips (biochemical elements). A recording head for use with an image recording apparatus ejects fluid ink. A coloring material ejection head for use with a display manufacturing apparatus ejects solutions of R (red), G (green), and B (blue) coloring materials. An electrode material ejection head for use with an electrode forming apparatus ejects liquid electrode material. Liquid-shaped electrode material is ejected from an electrode material ejection head for use with an electrode forming apparatus, and a bio-organic substance ejection head for use with a chip manufacturing apparatus ejects a solution of bio-organic substance.
Accurate control of the volume of a droplet to be ejected is essential for the liquid ejecting apparatus of this type. Because of manufacturing circumstances, variations tend to arise in the volume of a droplet to be ejected on a per-ejection-head basis or for each row of nozzles. In order to prevent occurrence of variations in the volume of a droplet to be ejected, the volume of a droplet to be ejected is controlled by use of information about a deviation in the volume of a droplet to be ejected. For instance, in the case of the image recording apparatus, variations in the ink amount cause a designed standard volume to deviate from the ink amount impacted per unit area. The density of a recorded image also deviates from a standard density. Therefore, a deviation in the ink amount to be ejected is acquired for each recording head, and the ink amount impacted is controlled by use of identification information showing the deviation (described on, e.g., pp. 4 to 5 and in FIG. 4 in Japanese Patent Publication No. 10-278360A). As a result, the ink amount impacted per unit area is made uniform, thereby enabling recording with superior image quality.
Strong desire exists for a speedup in ejection of a droplet from the liquid ejecting apparatus of this type. For this reason, actuation of piezoelectric elements (e.g., piezoelectric vibrators) provided on the ejection head at higher speed is desired. For example, an attempt has been made to increase the maximum drive frequency of a drive pulse from 13 kHz to 35 kHz approximately.
However, when the drive frequency of the drive pulse has been increased so as to become higher than the conventional drive frequency, the volume of a droplet to be ejected is found to change according to the drive frequency of a drive pulse. For instance, when a single drive pulse is supplied to a pressure generating element while a drive frequency of the drive pulse is changed, the ink amount is found to increase as the drive frequency is increased in a frequency range higher than a conventionally-used frequency band. This is considered to result from the state of a meniscus. More specifically, since the time interval from ejection of a droplet until ejection of the next droplet has become shorter, the next droplet is ejected before vibration of the meniscus, which has arisen immediately after ejection of the droplet, sufficiently disappears. Hence, a difference in the state of the meniscus is considered to be responsible for occurrence of a difference in the volume of a droplet to be ejected (i.e., the volume of a droplet). Further, the rate of increase in the volume of a droplet in a high frequency range is also found to vary from one recording head to another.
For these reasons, even when the number of droplets ejected per unit time is corrected on the basis of the identification information, mere use of the technique described in Japanese Patent Publication No. 10-278360A cannot prevent occurrence of a variation in the volume of a droplet impacted per unit area, which would otherwise occur in accordance with an employed frequency.
The invention has been conceived in view of the circumstances and provides a liquid ejecting head and a liquid ejecting apparatus, which can prevent occurrence of variations in the volume of a droplet impacted even when the frequency of a drive pulse which can be supplied is increased.
In order to achieve the above object, according to the invention, there is provided a liquid jetting head, comprising:
a pressure generating element, associated with a pressure chamber communicated with a nozzle orifice, the pressure generating element operable to generate pressure fluctuation in liquid contained in the pressure chamber to eject a liquid droplet from the nozzle orifice, when a drive signal is supplied thereto; and
an identifier, provided with ID information including a deviation of an ejected liquid amount from a designed value when a drive signal at a first, regular drive frequency is supplied.
Preferably, the ID information includes a deviation of an ejected liquid amount from the designed value when a drive signal at a second drive frequency, which is N-times (N is an integer not less than 2) of the first drive frequency, but is not higher than an operable maximum frequency, is supplied.
According to the invention, there is also provided a liquid jetting head, comprising:
a pressure generating element, associated with a pressure chamber communicated with a nozzle orifice, the pressure generating element operable to generate pressure fluctuation in liquid contained in the pressure chamber to eject a liquid droplet from the nozzle orifice, when a drive signal is supplied thereto; and
an identifier, provided with ID information including a deviation of an ejected liquid amount from a designed value when a drive signal at a drive frequency which is 1/N-times (N is an integer not less than 2) of a regular drive frequency is supplied.
According to the invention, there is also provided a liquid jetting head, comprising:
a pressure generating element, associated with a pressure chamber communicated with a nozzle orifice, the pressure generating element operable to generate pressure fluctuation in liquid contained in the pressure chamber to eject a liquid droplet from the nozzle orifice, when a drive signal is supplied thereto; and
an identifier, provided with ID information including a first deviation of an ejected liquid amount from a designed value when a drive signal at a first drive frequency which is N-times (N is an integer not less than 1) of a regular drive frequency is supplied, and a second deviation of an ejected liquid amount from a designed value when a drive signal at a second drive frequency which is 1/N-times (N is an integer not less than 2) of the regular drive frequency is supplied. Here, it is preferable that the first drive frequency is a half of the second drive frequency.
In the above configurations, it is preferable that: a plurality of nozzles are arranged so as to form a plurality of nozzle arrays; and the ID information is individually provided with respect to each of the nozzle arrays.
In the above configurations, it is preferable that: the liquid jetting head is operable under a plurality of operation modes which are distinguished from each other by a minimum ejected liquid amount; and the ID information is individually provided with respect to each of the operation modes.
In the above configurations, it is preferable that: the drive signal includes a first drive pulse for ejecting a liquid droplet of a first amount and a second drive pulse for ejecting a liquid droplet of a second amount greater than the first amount, which are selectively supplied to the pressure generating element to define an actual ejected amount of liquid droplet; and the ID information is determined based on either the first drive pulse or the second drive pulse. More preferably, the ID information is determined based on the second drive pulse.
In the above configurations, the identifier is provided on an exterior face of the liquid jetting head.
In the above configurations, the liquid jetting head further comprises a storage, which stores the ID information such that the stored ID information is electrically readable.
According to the invention, there is also provided a liquid jetting apparatus incorporating the above liquid jetting head, comprising:
a drive signal generator, which generates the drive signal;
a storage, which stores the ID information; and
an ejection controller, which supplies the generated drive signal to the pressure generating element, while adjusting an amount of liquid to be landed on a target per unit area, in accordance with the ID information stored in the storage.
According to the invention, there is provided a liquid jetting apparatus incorporating the above liquid jetting head, comprising:
a mode selector, which selects one of the operation modes;
a drive signal generator, which generates the drive signal in accordance with the selected operation mode;
a storage, which stores the ID information; and
an ejection controller, which supplies the generated drive signal to the pressure generating element, while selecting one of the ID information stored in the storage, in accordance with the selected operation mode.
Here, it is preferable that the ejection controller adjusts an amount of liquid to be landed on a target per unit area, in accordance with the selected ID information.
With the above configurations, the amount of liquid to be ejected at a frequency range employed with a high frequency can be made uniform by controlling the ID information at the time of ejection. Therefore, variations in the amount of liquid impacted per unit area can be effectively prevented.